1. Field of the Invention
The present invention relates to a fixing device to fix images on recording media, and an image forming apparatus, such as a printer, facsimile machine, copier, plotter, or multi-functional peripheral, employing the fixing device.
2. Discussion of the Background
Rendering visible image data using latent images formed using image forming apparatuses employing electrophotographic or electrostatic recording methods is used in a wide variety of fields.
For example, in the electrophotographic method, a latent image is formed on a photoreceptor according to image data by executing a charging process and an exposure process and then is developed with developer (e.g., toner) into a visible image, after which the image is recorded on a recording medium, such as a sheet of paper, by executing a transfer process and a fixing process.
In image forming apparatuses, such as printers, facsimile machines, copiers, plotters, or multi-functional peripherals having several of the foregoing functions, an unfixed image transferred onto the sheet is fixed thereon in the fixing process, and then the sheet is discharged as a printing output. Each of the image forming apparatuses includes a fixing device to execute the fixing process.
Fixing devices include a fixing roller, a heating roller heated by a heater, an endless belt wound around the fixing roller and the heating roller, a pressure roller that contacts an outer circumferential surface of the belt and pressures the fixing roller via the belt. The endless belt and the pressure roller contact and a nip area is formed in the contact area.
In this fixing device, when the sheet passes the nip area, the image is fixed on the sheet with heat and pressure by fusing an unfixed image. Alternatively, in other fixing devices, multiple belts press against each other to form the fixing nip, similarly to the above-described configuration.
These belt-fixing devices have the problem that the endless belt approaches a side of the belt-fixing device in the direction of the axis around which the belt is rotating. If the endless belt continues rotating in such a state (i.e. the belt continues to approach the side of the belt-fixing device in the direction of the axis), the endless belt may collide with the side board of the belt-fixing device and the endless belt may be damaged.